Yet in Britain, with a 3 kW kettle, I've never managed to trip it, with a combination of laundry machine, electric oven, microwave, dishwasher. Is there no circuit breaker limit?
Rings are more complex to test, and have nasty failure modes. I'd argue that they should only be used in said small flats, and that 20A bus/radial runs should be used in larger builds. i.e. any modern house, rather than a flat. Said run the supplying all of the sockets in any given room, it does though require a larger "consumer unit".
The rings have a 30A (or now 32A) at the "consumer unit" (distribution fuse box) with two cables running in a loop around all sockets in the circuit. The cables have traditionally been 2.5mm, and open clipped, so rated at around 27A (based upon preventing overheating).
Hence when operating properly, the wiring in the circuit can carry 54A, the circuit is fused at 30A (or 32A) to protect the cable, and an individual load is limited to 13A (being the highest cartridge fuse commonly available).
Have a look here: https://www.diydoctor.org.uk/projects/cablesizes.htm
Then, standard ring circuit is 32A, and individual sockets are limited to 13A (via fuse in plug). So you will need to have 2 kettles on on the same circuit and then add a third device pulling not an insignificant amount of power (32 - 2x13 = 6A) before the breaker trips. This will be safe if the ring circuit is not faulty as they are usually wired with two 2.5mm2 cables (two because it's a ring) that have a standard rating of 24A each...
- dedicated 50A 240V for an electric stove or oven (unless gas service is present)
- dedicated 20A 120V each for the fridge, microwave, dishwasher, disposal (the latter being uncommon outside the US and Canada). The last two often share a circuit.
- two 20A countertop circuits with GFCI protection (what the Brits call 'RCD' - the difference being ours trip at 5mA vs 30mA and won't knock out half the house.)
A typical British kitchen will have a ton of sockets (although never enough), to plug in a fridge (or two, or three), a microwave (or several - they rarely goes about 1kW anyway), a dishwasher, a washing machine, a tumble dryer (UK kitchens tend to have washers and dryers, rather than bathrooms. Larger houses have separate utility rooms)
The only thing on a dedicated circuit would be a hard-wired oven.
A software analogy would be running all your services on separate VMs, as opposed to running them all on a single server which could go down at once.
Brits don't even put outlets in the bathroom, minus a current-limited transformer-isolated one for an electric razor.
Has never been an issue anywhere I lived in the UK. As I understand it they have been putting in 30A/230V ring circuits as standard for 75 years now.
Wait, really? That’s seriously underpowered, though I guess if you never need electric stoves or heating it could be somewhat usable. An ex-Soviet big-city apartment building will usually support 40A (~9kW) per apartment, and in France I had the impression that the values were similar—except for student dorms, which are supplied and wired like apartment buildings despite the density of occupants being 3x that or more, because apparently the builders could not into engineering and the uni authorities find it easier to blame the occupants (yes, I’m still a bit salty about that).
I have always wondered if those limits and the high electricity costs are because Italy abolished nuclear energy post-Chernobyl, doesn't have a massive oil and gas operation, so most of it is imported at a premium.
We should thank whoever came up with the idea of abolishing nuclear power in Italy. What a big mistake!
> if you never need electric stoves or heating it could be somewhat usable
Heating and stoves in Italy are usually gas-powered. Ovens and kettles are electric but normally do not exceed 3.3 kW, however, we need to be careful not to use too many high-consumption appliances together (e.g., oven and washing machine).
The introduction of increasingly restrictive energy classes for electric appliances in recent years has mitigated the problem to some extent anyway.
You guys really need to get on the solar panels, though.
In the Soviet system, usually not. There are often several downstream circuits with their own 20A or so breakers and wiring (e.g.: kitchen stove, normal kitchen sockets, bathroom sockets and lighting, other rooms’ sockets, everything non-wet lighting), but each apartment is normally supplied from a single phase. On the other hand, different apartments on the same floor (or different single-family homes on the same street, etc.) might indeed be supplied from different phases. Normal (Schuko) wall sockets are most frequently 16A (so yes, 3kW kettles max), stove sockets (and circuits) might be up to 32A, still single-phase.
(That’s not to say the system is ideal, of course. E.g. GFCIs have become common only in the past fifteen years or so, and in a country-home setting I’ve actually encountered disposable screw-socket [IEC 60269] fuses.)
In a perfect world a ring circuit is a clever invention - it offers a circuit that can safely deliver about 7.3kW with hardly any more copper than normally could deliver about 4.6kW.
However in practice they have a hidden failure mode - if you break the ring they will carry on working apparently without problem except it’s quite possible that you now have overheating cables in a wall somewhere. In the real world houses are full of changes (both DIY and professional) that inadvertently break the ring and it’s not at all uncommon to see in a house with even modest refurb works having been done.
That's massive.
> I'm struggling to understand how the British grid works
I live in an early 20th century apartment in San Francisco and I quickly learned not to run my 1.8kW kettle at the same time as my 1.2kW microwave as it would consistently trip the power.
More annoying is when the fridge compressor motor starts up while running either as that also trips the power.